alar

From Latin ala (wing), which also gave us aisle and aileron.
Earliest documented use: 1791.

USAGE:

“Fred Urquhart began in 1937 to experiment with different ways of marking
these delicate insects in order to study their migration patterns,
eventually developing and refining the method of applying an alar tag to
the monarch’s wing.”
Gerry Rising; A Salute to the King of the Monarch Butterflies;
Buffalo News (New York); Dec 16, 1996.